CN110868132A

CN110868132A - Engine with permanent magnet motor

Info

Publication number: CN110868132A
Application number: CN201910791301.3A
Authority: CN
Inventors: 罗伯特·查尔斯·弘; 潘迪; 巴勃罗·加百利·皮亚扎·加拉扎; 保罗·罗伯特·杰明
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2018-08-27
Filing date: 2019-08-26
Publication date: 2020-03-06
Anticipated expiration: 2039-08-26
Also published as: US20200067383A1; CN110868132B; US10978934B2; EP3618263A1; CN116683831A

Abstract

A method for operating a permanent magnet motor of an engine, the method comprising: determining a fault condition of the permanent magnet motor; in response to determining the fault condition of the permanent magnet motor, the magnetism of one or more permanent magnets of the permanent magnet motor is reduced by increasing the temperature of the one or more permanent magnets.

Description

Engine with permanent magnet motor

Technical Field

The present subject matter generally relates to an engine having a permanent magnet machine.

Background

A typical aircraft propulsion system includes one or more gas turbine engines. For certain propulsion systems, the gas turbine engine typically includes a fan and a core arranged in flow communication with each other. In addition, the core of a gas turbine engine typically includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided from the fan to the inlet of the compressor section, wherein one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and combusted within the combustion section to provide combustion gases. Combustion gases are channeled from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then directed through an exhaust section, e.g., to the atmosphere.

For at least some propulsion systems including the gas turbine engines described above, it may be beneficial to include an electrically powered fan to supplement the propulsion power provided by one or more of the gas turbine engines included with the propulsion system. However, including a sufficient amount of energy storage device and propulsion system to power the fan may be prohibitive in space and weight. Accordingly, at least some propulsion systems include one or more electric machines that are rotatable with one or more of the gas turbine engines to generate electrical power to drive the electric fan during operation.

Furthermore, the inventors of the present disclosure have determined that utilizing permanent magnet motors may have certain benefits over other motor configurations. These benefits may include power density, efficiency, and simplicity. However, one negative characteristic of permanent magnet motors relates to their behavior after internal coil failure. In particular, after such an event, the permanent magnet motor may fail as long as the rotor is rotating, possibly resulting in significant drag of the drive motor and heat generation within the failed coil. This unwanted generation can have negative consequences and in the prior art, the only way to stop this unwanted generation is to stop the rotation (i.e. turn off the drive engine). This action may have the further negative consequence of a loss of thrust and power. Other types of motors do not have the same problem because their rotors can be effectively deactivated.

Accordingly, a safety system for a permanent magnet electric machine that may be used with an engine (such as a gas turbine engine) to overcome the above-described obstacles would be useful.

Disclosure of Invention

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one exemplary aspect of the present disclosure, a method for operating a permanent magnet electric machine of an engine is provided. The method comprises the following steps: determining a fault condition of the permanent magnet motor; in response to determining the fault condition of the permanent magnet motor, the magnetism of the one or more permanent magnets is reduced by increasing the temperature of the one or more permanent magnets of the permanent magnet motor.

In certain exemplary embodiments, the engine is an internal combustion engine.

In certain exemplary embodiments, the engine is at least one of a turboshaft engine, a turboprop engine, or a turbofan engine.

In certain exemplary embodiments, the engine is configured to generate a maximum amount of power during operation, wherein the permanent magnet motor is capable of extracting the maximum amount of power from the engine, and wherein the maximum amount of power that the permanent magnet motor is capable of extracting from the engine is between about 2.5% and about 75% of the maximum amount of power that the engine is configured to generate during operation.

For example, in certain exemplary aspects, the maximum amount of power that the permanent magnet motor can extract from the engine is greater than about 25% of the maximum amount of power the engine is configured to generate during operation.

In certain example embodiments, determining a fault condition of a permanent magnet motor includes determining an internal coil fault of the permanent magnet motor.

In certain example embodiments, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises driving a current through a stator assembly of the permanent magnet machine to induce eddy current losses in a rotor assembly of the permanent magnet machine.

For example, in certain exemplary aspects, the permanent magnet motor defines a designed current frequency operating range, and wherein driving current through the stator assembly of the permanent magnet motor to cause eddy current losses includes driving current through the stator assembly of the permanent magnet motor at a frequency different than the designed current frequency operating range.

In certain example embodiments, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises providing a heated fluid to the permanent magnet motor.

For example, in certain exemplary aspects, providing heated fluid to the permanent magnet motor includes providing bleed air to the permanent magnet motor.

In certain example embodiments, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises reducing cooling of the permanent magnet machine using a thermal management system.

For example, in certain exemplary aspects, using the thermal management system to reduce cooling of the permanent magnet electric machine includes bypassing a heat sink heat exchanger of the thermal management system.

In certain example embodiments, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises injecting a fluid into an air gap of the permanent magnet machine.

For example, in certain exemplary aspects, the fluid defines a viscosity greater than that of air.

In certain exemplary embodiments, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises adding between about five kilowatts and about five hundred kilowatts of thermal energy.

In certain example embodiments, a permanent magnet electric machine includes a rotor assembly having a plurality of laminations and a shaft, wherein the plurality of laminations fit onto the shaft, and wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets includes reducing the contact pressure between the plurality of laminations and the shaft.

For example, in certain exemplary aspects, the engine includes a thermal management system for providing cooling fluid through one or more openings in the shaft.

In an exemplary embodiment of the present disclosure, an engine defining an axis is provided. The engine includes: a fixing member; a rotating member rotatable about an axis of the engine relative to the stationary member; a permanent magnet electric machine comprising a stator assembly coupled to a stationary component and a rotor assembly coupled to a rotating component, the rotor assembly comprising one or more permanent magnets; a controller operable with the permanent magnet motor, the controller configured to determine a fault condition of the permanent magnet motor and increase a temperature of one or more permanent magnets of the permanent magnet motor in response to determining the fault condition.

In certain exemplary embodiments, the engine further comprises an electrical transmission bus in electrical communication with the permanent magnet motor, wherein the controller is further operatively connected to the electrical transmission bus.

For example, in certain exemplary embodiments, the engine is configured to generate a maximum amount of power during operation, wherein the permanent magnet motor is capable of extracting the maximum amount of power from the engine, and wherein the maximum amount of power that the permanent magnet motor is capable of extracting from the engine is between about 2.5% and about 75% of the maximum amount of power that the engine is capable of generating during operation.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Drawings

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine according to an exemplary embodiment of the present disclosure.

FIG. 2 is a schematic close-up view of a gas turbine engine and a permanent magnet machine according to an exemplary embodiment of the present disclosure.

FIG. 3 is a schematic close-up view of a gas turbine engine and a permanent magnet machine according to another exemplary embodiment of the present disclosure.

FIG. 4 is a schematic close-up view of a gas turbine engine and a permanent magnet machine according to yet another exemplary embodiment of the present disclosure.

FIG. 5 is a schematic close-up view of a gas turbine engine and a permanent magnet machine according to yet another exemplary embodiment of the present disclosure.

FIG. 6 is a flow chart of a method for operating an engine according to an exemplary aspect of the present disclosure.

Detailed Description

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar reference numbers have been used in the drawings and the description to refer to the same or similar parts of the invention.

As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one element from another, and are not intended to denote the position or importance of the various elements.

The terms "front" and "rear" refer to relative positions within a component or system, and refer to the normal operating attitude of the component or system. For example, with respect to a robotic arm, front refers to a position closer to the distal end of the robotic arm, and back refers to a position closer to the root end of the robotic arm.

Unless otherwise specified herein, the terms "coupled," "secured," "attached," and the like refer to a direct coupling, securing, or attachment, as well as an indirect coupling, securing, or attachment through one or more intermediate components or features.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms (e.g., "about," "approximately," and "substantially") is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of a method or machine for constructing or manufacturing the component and/or system. For example, approximate language may refer to being in the range of 10%.

Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

Referring now to the drawings, in which like numerals represent like elements throughout the several views, FIG. 1 is a schematic cross-sectional view of an engine according to an exemplary embodiment of the present disclosure. More specifically, for the embodiment of fig. 1, the engine is a gas turbine engine, and more specifically, the gas turbine engine is a high bypass turbofan jet engine 10, referred to herein as "turbofan engine 10". As shown in FIG. 1, turbofan engine 10 defines an axial direction A (extending parallel to a longitudinal centerline 12 provided for reference), a radial direction R, and a circumferential direction (i.e., a direction extending about axial direction A; not shown). Generally, the turbofan 10 includes a fan section 14 and a turbine 16 disposed downstream of the fan section 14.

The illustrated exemplary turbine 16 generally includes a substantially tubular outer casing 18 defining an annular inlet 20. The outer housing 18 encloses in serial flow relationship: a compressor section including a booster or Low Pressure (LP) compressor 22 and a High Pressure (HP) compressor 24; a combustion section 26; a turbine section including a High Pressure (HP) turbine 28 and a Low Pressure (LP) turbine 30; the exhaust nozzle section 32 is injected. The compressor section, combustion section 26, and turbine section together define a core air flow path 37, the core air flow path 37 extending from the annular inlet 20 through the LP compressor 22, HP compressor 24, combustion section 26, HP turbine section 28, LP turbine section 30, and injection exhaust nozzle section 32. A High Pressure (HP) shaft or spool 34 drivingly connects the HP turbine 28 to the HP compressor 24. A Low Pressure (LP) shaft or spool 36 drivingly connects the LP turbine 30 to the LP compressor 22.

For the depicted embodiment, fan section 14 includes a variable pitch fan 38 having a plurality of fan blades 40 coupled to a disk 42 in a spaced apart manner. As shown, fan blades 40 extend generally outward from disk 42 in a radial direction R. Each fan blade 40 is rotatable about a pitch axis P relative to the disk 42 by virtue of the fan blades 40 being operatively coupled to a suitable actuating member 44, which actuating members 44 are configured to collectively change the pitch of the fan blades 40 in unison. Fan blades 40, disk 42, and actuating member 44 together may be rotated about longitudinal axis 12 by LP shaft 36 passing through power gearbox 46. Power gearbox 46 includes a plurality of gears for reducing the rotational speed of LP shaft 36 to a more efficient rotational fan speed.

Still referring to the exemplary embodiment of FIG. 1, disk 42 is covered by a rotatable forward nacelle 48, the forward nacelle 48 being aerodynamically shaped to promote airflow over the plurality of fan blades 40. Additionally, the exemplary fan section 14 includes an annular fan casing or nacelle 50 that circumferentially surrounds at least a portion of the fan 38 and/or the turbine 16. It should be appreciated that for the depicted embodiment, the nacelle 50 is supported relative to the turbine 16 by a plurality of circumferentially spaced outlet guide vanes 52. Further, a downstream section 54 of nacelle 50 extends over an exterior portion of turbine 16 to define a bypass airflow passage 56 therebetween.

During operation of turbofan engine 10, a quantity of air 58 enters turbofan 10 through nacelle 50 and/or an associated inlet 60 of fan section 14. As a quantity of air 58 passes through fan blades 40, a first portion of air 58, as indicated by arrow 62, is channeled or directed into bypass airflow passage 56, and a second portion of air 58, as indicated by arrow 64, is channeled or directed into LP compressor 22. The ratio between the first portion of air 62 and the second portion of air 64 is commonly referred to as the bypass ratio. Then, as the second portion of air 64 is channeled through High Pressure (HP) compressor 24 and into combustion section 26, the pressure of second portion of air 64 increases, where it is mixed with fuel and combusted to provide combustion gases 66.

Combustion gases 66 are channeled through HP turbine 28, wherein a portion of thermal and/or kinetic energy from combustion gases 66 is extracted via successive stages of HP turbine stator vanes 68 coupled to casing 18 and HP turbine rotor blades 70 coupled to HP shaft or spool 34, thereby rotating HP shaft or spool 34, thereby supporting operation of HP compressor 24. The combustion gases 66 are then channeled through LP turbine 30, wherein a second portion of thermal and kinetic energy is extracted from combustion gases 66 via successive stages of LP turbine rotor blades 72 coupled to LP shaft or spool 36, thereby rotating LP shaft or spool 36. Thereby supporting operation of the LP compressor 22 and/or rotation of the fan 38.

Subsequently, the combustion gases 66 are directed through the jet exhaust nozzle section 32 of the turbine 16 to provide propulsive thrust. At the same time, as first portion of air 62 is channeled through bypass airflow passage 56 prior to being discharged from fan nozzle exhaust section 76 of turbofan 10, the pressure of first portion of air 62 is substantially increased, providing a majority of the propulsive force for turbofan engine 10. HP turbine 28, LP turbine 30, and jet exhaust nozzle section 32 at least partially define a hot gas path 78 for directing combustion gases 66 through turbine 16.

In addition, the exemplary turbofan 10 shown includes a permanent magnet motor 80 that is rotatable with the turbofan 10. Specifically, for the illustrated embodiment, permanent magnet motor 80 is coaxially mounted to LP shaft 36 and is rotatable with LP shaft 36 (for the illustrated embodiment, LP shaft 36 also rotates fan 38 through power gearbox 46). As used herein, "coaxial" refers to axial alignment. However, it should be appreciated that in other embodiments, the axis of permanent magnet motor 80 may be radially offset from the axis of LP shaft 36, and may also be oblique to the axis of LP shaft 36, such that permanent magnet motor 80 may be positioned at any suitable location at least partially inward of core air flow path 37.

Permanent magnet machine 80 includes a rotor assembly 82 and a stator assembly 84. As will be discussed below, the rotor assembly 82 may generally include a plurality of permanent magnets 88 such that it may be referred to as a permanent magnet rotor assembly 82. Additionally, the stator assembly 84 may generally include a plurality of coils 86, the plurality of coils 86 operable with a plurality of permanent magnets 88 of the rotor assembly 82. When power is provided to the plurality of coils 86 of the stator assembly 84, the permanent magnet motor 80 may operate to add torque to the turbofan 10 via the LP shaft 36. In contrast, in other exemplary aspects, the plurality of coils 86 of the stator assembly 84 may operate to extract electrical power, converting the torque of the turbofan 10, and more specifically, the torque of the LP shaft 36, into electrical power.

It should also be appreciated that, in certain exemplary embodiments, turbofan engine 10 may be integrated into a propulsion system. With such an exemplary embodiment, permanent magnet motor 80 may be electrically connected or connectable to one or more electric propulsion devices (e.g., one or more electric fans), one or more electrical power storage devices, etc. of the propulsion system.

However, it should be appreciated that the exemplary turbofan engine 10 depicted in FIG. 1 is merely exemplary, and that in other exemplary embodiments, the turbofan engine 10 may have any other suitable configuration. For example, in other exemplary embodiments, turbofan engine 10 may include any other suitable number or configuration of shafts or spools, compressors, turbines, etc., and/or may eliminate, for example, power gearbox 46 and/or pitch change mechanism 44, etc. Accordingly, it should be appreciated that in other exemplary embodiments, turbofan engine 10 may alternatively be configured as a direct drive turbofan engine, a fixed pitch turbofan engine, or the like. Moreover, in other exemplary embodiments, turbofan engine 10 may be configured as any other suitable gas turbine engine, such as a turbojet engine, turboshaft engine, turboprop engine, or the like. Furthermore, in other embodiments, the turbofan engine may be configured as any other suitable engine, such as an electric propulsion fan for an aircraft propulsion system or any form of combustion engine (e.g., an internal combustion engine). With such a configuration, the engine may not include any turbomachinery, but instead may generally include the fan 38 and the permanent magnet motor 80.

Referring now to fig. 2, a close-up view of the exemplary permanent magnet electric machine 80 of fig. 1 embedded within the engine of fig. 1 is provided. More specifically, for the depicted embodiment and as described above, permanent magnet motor 80 is embedded within the turbine section of turbofan engine 10, at a location inward of core air flow path 37, and is positioned at least partially inside or aft of the turbine section in axial direction a. Of course, as discussed above, in other exemplary embodiments, permanent magnet motor 80 may alternatively be positioned at any other suitable location within turbofan engine 10, such as within the compressor section, forward of the compressor section, radially outward of core air flow path 37 (e.g., under a fairing of turbine 16, such as a portion of an accessory gearbox), and so forth.

More specifically, for the exemplary embodiment shown, permanent magnet motor 80 is positioned inside core air flow path 37 and at least partially aft of LP turbine 30 of the turbine section of turbofan engine 10. Briefly, as will be appreciated, the exemplary LP turbine 30 shown generally includes a plurality of LP turbine rotor blades 90 and a plurality of LP turbine stator vanes 92 (although only one is shown). Moreover, it should be appreciated that each of the plurality of LP turbine rotor blades 90 is generally coupled to a respective rotor 94, wherein the plurality of respective rotors 94 are coupled to LP shaft 36 or otherwise rotate with LP shaft 36.

Further, with the embodiment of FIG. 2, turbofan engine 10 generally includes a rotating component and a stationary component. The rotating components may rotate with a compressor within a compressor section (not shown) of turbofan engine 10 and/or a turbine within a turbine section of turbofan engine 10. In contrast, the stationary component may be any suitable component configured to remain stationary with respect to the various rotating components of the compressor and turbine.

For the exemplary embodiment shown, the stationary component is part of a structural support member 96 of turbofan engine 10, structural support member 96 being configured as part of and extending from a rear frame strut 98 of the rear frame assembly. The aft strut 98 extends through the core air flow path 37 of the turbofan engine 10 and is configured to provide structural support to the turbofan engine 10. The structural support member 96 also extends forwardly to support a rear engine bearing 100 — the rear engine bearing 100 rotatably supports the rear end of the LP shaft 36.

In addition, as described above, permanent magnet electric machine 80 generally includes a rotor assembly 82 and a stator assembly 84. Rotor assembly 82 is coupled to a rotating component of the gas turbine engine, and stator assembly 84 is coupled to a stationary component of turbofan engine 10. More specifically, for the depicted embodiment, the rotating component to which rotor assembly 82 is coupled is LP shaft 36 of turbofan engine 10 such that rotor assembly 82 is rotatable with LP shaft 36. Instead, the stationary component to which the stator assembly 84 is coupled is the structural support member 96 of the turbine section.

More specifically, rotor assembly 82 generally includes a rotor 102 and a shaft 104. The rotor 102 may be formed of a plurality of sequentially arranged laminations 142 (see reference circle a in fig. 3 below), the laminations 142 being arranged, for example, axially on the shaft 104, wherein the plurality of sequentially arranged laminations 142 mount the plurality of permanent magnets 88 of the rotor assembly 82. A plurality of permanent magnets 88 may be arranged circumferentially about the axis of permanent magnet machine 80 (which, for the depicted embodiment, is aligned with axis 12 of turbofan engine 10). Similarly, the stator assembly 84 generally includes a stator 106 and a shaft 108. Stator 106 includes a plurality of coils 86, which may also be arranged circumferentially about the axis of permanent magnet motor 80. The rotor assembly 82 is rotatable relative to the stator assembly 84 during operation, and for the illustrated embodiment is rotatably supported relative to the stator assembly 84 by a front ball bearing 110 and a rear ball bearing 112. However, in other embodiments, any other suitable configuration may be provided for rotatably supporting rotor assembly 82 relative to stator assembly 84 (e.g., any other suitable configuration of mechanical bearings, use of suitable air bearings, etc.).

In addition, the permanent magnet motor 80 is electrically connected to an electrical transmission bus 114. The electrical transmission bus 114 includes electrical wires 116, and for the illustrated embodiment, the electrical wires 116 extend through the core air flow path 37 and, more specifically, through the rear posts 98. The electrical wires 116 are electrically coupled to the stator assembly 84 of the permanent magnet motor 80. The illustrated exemplary electrical transmission bus 114 generally includes power electronics 118 in communication with electrical wires 116 that may be used to manipulate power provided to the permanent magnet motor 80, or to extract power from the permanent magnet motor 80, and more specifically, to the stator assembly 84 of the permanent magnet motor 80 or from the stator assembly 84 of the permanent magnet motor 80.

Additionally, the electrical transmission bus 114 includes one or more sensors operable with the electrical wires 116, the power electronics 118, or both. More specifically, for the embodiment shown, the electrical transmission bus 114 includes a first sensor 120 operable with the electrical wires 116 (i.e., for sensing data from the electrical wires 116) and a second sensor 122 operable with the power electronics 118 (i.e., for sensing data from the power electronics 118). The first sensor 120, the second sensor 122, or both may be configured to sense various parameters of the electrical transmission bus 114 and/or the power electronics 118 to determine one or more operational parameters of the permanent magnet motor 80. For example, first sensor 120, second sensor 122, or both may be used to determine an amount of power extracted from permanent magnet motor 80, an amount of power provided to permanent magnet motor 80, a voltage of such power, a current magnitude of such power, a frequency of such current, and/or the like.

Briefly, a controller 124 in operable communication with the electrical transmission bus 114 is also provided. It is worthy to note that although controller 124 is depicted as being physically located separately from turbofan engine 10 and permanent magnet motor 80, in other embodiments, controller 124 may be located or otherwise integrated into turbofan engine 10, aircraft that includes turbofan engine 10, permanent magnet motor 80, or the like.

The example controller 124 generally includes a network interface 126. Network interface 126 may operate with any suitable wired or wireless communication network for data communication with, for example, turbofan engine 10, permanent magnet motor 80, other components of electrical transmission bus 114, and/or other components or systems not shown. As depicted using dashed lines in fig. 2, for the depicted embodiment, the network interface 126 utilizes a wireless communication network to communicate data with other components (including the first sensor 120, the second sensor 122, and the power electronics 118). In this manner, the controller 124 may control the operation of the power electronics 118. Of course, it should be understood that although the network interface 126 utilizes a wireless communication network for the embodiment of fig. 2, in other embodiments, the network interface 126 may instead utilize a wired communication network, or a combination of wired and wireless communication networks.

Still referring to fig. 2, the example controller 124 also includes one or more processors 128 and memory 130. The memory 130 stores data 132 that is accessible by the one or more processors 128. The one or more processors 128 may include any suitable processing device, such as a microprocessor, microcontroller 124, integrated circuit, logic device, and/or other suitable processing device. The one or more memory devices 130 may include one or more computer-readable media, including but not limited to non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices. The data 132 may include instructions that, when executed by the one or more processors 128, cause the system 204 to perform functions. One or more exemplary aspects of these functions may be described below with respect to the exemplary method 200 of fig. 6. The instructions within the data 132 may be any set of instructions that, when executed by the one or more processors 128, cause the one or more processors 128 to perform operations. In some exemplary embodiments, the instructions within the data 132 may be software written in any suitable programming language, or may be implemented in hardware. Additionally, and/or alternatively, instructions may be executed in logically and/or virtually separate threads on processor 128. Memory device 130 may also store other data 132 that may be accessed by processor 128.

However, it should be understood that the exemplary electrical transmission bus 114 (including the power electronics 118 and the wires 116), the controller 124, and the sensors 120,122 are provided as examples only. In other exemplary embodiments, one or more of these components may be configured in any other suitable manner and/or any other suitable configuration may be provided to control operations associated with permanent magnet motor 80.

Still referring to FIG. 2, it should be appreciated that permanent magnet motor 80 may be configured to extract a relatively high amount of power from turbofan engine 10. For example, turbofan engine 10, or more specifically, turbine 16 of turbofan engine 10, may be configured to generate a maximum amount of power during operation. The maximum amount of power may be the rated power level of the turbine 16. In addition, permanent magnet motor 80 is capable of extracting a maximum amount of power from turbofan engine 10 (or more specifically, from turbine 16 of turbofan engine 10) during operation. For example, the maximum amount of power that permanent magnet motor 80 is capable of extracting may be set based on design parameters of permanent magnet motor 80, with permanent magnet motor 80 being designed to allow permanent magnet motor 80 to operate without significant degradation. In at least certain exemplary embodiments, the maximum amount of power that permanent magnet motor 80 is capable of extracting from turbofan engine 10 (or, more specifically, from turbine 16) is between about 2.5% and about seventy-five percent (75%) of the maximum amount of power that turbofan engine 10 (or, more specifically, turbine 16 of turbofan engine 10) is configured to produce during operation. For example, in at least certain exemplary embodiments, the maximum amount of power that permanent magnet motor 80 is capable of extracting from turbofan engine 10 is greater than about three percent (3%), such as greater than about five percent (5%), such as greater than about ten percent (10%), such as greater than about twenty-five percent (25%), of the maximum amount of power that turbofan engine 10 is configured to generate during operation.

For example only, turbofan engine 10 may be rated to produce 40,000 horsepower, and permanent magnet motor 80 may be capable of drawing about 1,500 kilowatts or about 2,000 horsepower. Of course, in other embodiments, these numbers may vary widely (e.g., the gas turbine engine may be significantly more or less powerful, and/or permanent magnet machine 80 may be significantly more or less powerful). In any event, this may allow a desired amount of power to be provided to, for example, an electric fan of a propulsion system including turbofan engine 10 and permanent magnet motor 80, and/or any other suitable power sink of an aircraft.

However, by utilizing such a relatively strong permanent magnet motor 80, failure of the permanent magnet motor 80 may create an undesirably high resistance on the turbofan engine 10, and may generate an undesirably high level of heat. For example, permanent magnet machine 80 may experience an internal coil fault (i.e., a short circuit of the stator windings of stator assembly 84) if, for example, insulation of coil 86 breaks down. In this case, permanent magnet motor 80 may extract power from turbofan engine 10 without generating a corresponding amount of electrical power for the propulsion system. For example, depending on the severity of the internal coil failure of the permanent magnet motor 80, the permanent magnet motor 80 may not generate any power while still extracting a relatively high amount of power from the turbofan engine 10, e.g., up to the maximum amount of power that the permanent magnet motor 80 is capable of extracting, as described above (thus acting a significant drag on the engine). Notably, in certain exemplary embodiments, the internal coil fault may be determined by the controller 124 based on data sensed by one or more sensors (i.e., the first sensor 120 and the second sensor 122 of the illustrated embodiment). Additionally, it should be appreciated that internal coil failure may generate relatively high heat (which may lead to further damage). Accordingly, in certain embodiments, an internal coil fault may be determined by controller 124 based on sensed data indicative of the temperature of permanent magnet motor 80, or sensed data of a component or system indicative of the temperature of permanent magnet motor 80.

Further, given that the permanent magnets 88 are used with the rotor assembly 82, the permanent magnets 88 may not be "switched off" as with other types of motors. Accordingly, the system of the present disclosure is configured to reduce the magnetic properties of one or more permanent magnets 88 of permanent magnet motor 80, or more specifically, permanent magnets 88 of rotor assembly 82 of permanent magnet motor 80 in response to determining a fault condition of permanent magnet motor 80 (e.g., an internal coil fault-although it may be appropriate under other fault conditions of permanent magnet motor 80). More specifically, for the illustrated embodiment, the system of the present disclosure is configured to reduce the magnetic properties of the permanent magnets 88 by increasing the temperature of the rotor assembly 82 of the permanent magnet motor 80, and more specifically, the temperature of the permanent magnets 88 of the rotor assembly 82.

Specifically, for the depicted embodiment, the system is configured to utilize electric/induction to reduce the magnetic properties of the permanent magnet 88. For example, for the depicted embodiment, the system is configured to increase the temperature of the one or more permanent magnets 88 by driving current through the stator 106 of the stator assembly 84 of the permanent magnet motor 80 to induce eddy current losses. For example, permanent magnet motor 80 may define a designed current frequency operating range. As used herein, the term "designed current frequency operating range" refers to the current frequency range of electrical power that permanent magnet motor 80 is configured to generate when extracting power from turbofan engine 10, and/or the current frequency range of electrical power that permanent magnet motor 80 is capable of receiving during normal operation when adding power to turbofan engine 10. With the present disclosure, the system may also be configured to increase the temperature of one or the permanent magnets 88 by driving current through the stator 106 of the stator assembly 84 at a frequency greater than the designed current frequency operating range. As described above, this may further cause eddy current losses, which in turn may increase the temperature within permanent magnet motor 80, and more significantly within rotor assembly 82.

Notably, it should be appreciated that the permanent magnets 88 of the rotor assembly 82 each generally define a curie temperature. The curie temperature refers to a temperature at which the magnetic force of the permanent magnet 88 is irreversibly reduced or completely lost. Thus, in certain embodiments, increasing the temperature of the permanent magnet 88 may include increasing the temperature of the permanent magnet above its corresponding curie temperature.

For example, in at least some example embodiments, to increase the temperature of the permanent magnets 88 of the permanent magnet motor 80, the system may increase thermal energy to the permanent magnet motor 80 between approximately five (5) kilowatts and approximately five hundred (500) kilowatts. More specifically, in at least some embodiments, the system can add at least about ten (10) kilowatts of thermal energy, such as at least about twenty-five (25) kilowatts of thermal energy.

It should be appreciated that by increasing the temperature in this manner, the system may irreversibly reduce or eliminate the magnetism of the permanent magnets 88 of the rotor assembly 82 of the permanent magnet motor 80. However, it may be desirable to permanently damage permanent magnet motor 80 in order to reduce or eliminate drag permanent magnet motor 80 may have on turbofan engine 10 during flight, for example, of an aircraft containing turbofan engines 10 having permanent magnet motors 80 experiencing, for example, internal coil failure. For example, using the numbers provided in the non-limiting example above, it may be more desirable to permanently damage the motor 80 to avoid the long term drag of approximately 2,000 horsepower on a 40,000 horsepower engine.

Moreover, it should be understood that the exemplary turbofan engine 10 and permanent magnet motor 80 described above with reference to fig. 1 and 2 are provided by way of example only. In other exemplary embodiments, turbofan engine 10 and permanent magnet motor 80 may alternatively have any other suitable configuration. For example, in other embodiments, any other suitable means for increasing the temperature of one or more permanent magnets 88 of permanent magnet motor 80 may be provided to reduce the magnetic properties of such permanent magnets 88 in response to determining a fault condition of permanent magnet motor 80.

For example, fig. 3-5 provide various alternative exemplary embodiments of turbofan engine 10 and permanent magnet motor 80 described above with reference to fig. 1 and 2. Each of the embodiments of fig. 3-5 may generally be constructed in substantially the same manner as the embodiment described above with reference to fig. 1 and 2. For example, each of the exemplary turbofan engines 10 depicted in fig. 3-5 generally includes a permanent magnet electric machine 80 having a rotor assembly 82 coupled to a rotating component of the turbofan engine 10 (i.e., the LP shaft 36 of the illustrated embodiment) and a stator assembly 84 coupled to a stationary component of the turbofan engine 10 (i.e., the structural support member 96 of the illustrated embodiment). The stator assemblies 84 of the permanent magnet electric machine 80 each include a plurality of coils 86, and each coil 86 is electrically coupled to a respective electrical transmission bus 114 via electrical wires 116. Additionally, rotor assemblies 82 of permanent magnet electric machine 80 each generally include a rotor 102, rotor 102 having a plurality of permanent magnets 88 and a rotor shaft 104.

With particular reference to FIG. 3, turbofan engine 10 also includes a thermal management system 134 for permanent magnet motor 80. For the embodiment of fig. 3, thermal management system 134 utilizes cooling airflow to maintain the temperature of permanent magnet motor 80 within a desired operating temperature range during normal operation. For example, the thermal management system 134 generally includes an inlet duct 136, and the inlet duct 136 may receive a flow of bleed air from, for example, a compressor section of the turbofan engine 10. The thermal management system 134 may also include a heat exchanger (not shown) for reducing the temperature of such bleed air flow. As schematically shown, shaft 104 of rotor assembly 82 is configured as a hollow shaft 104 defining an opening 138 extending along its length (i.e., in an axial direction a of turbofan engine 10). An inlet duct 136 of thermal management system 134 is positioned in airflow communication with an opening 138 in rotor shaft 104 such that inlet duct 136 may provide a cooling airflow to and through opening 138 of rotor shaft 104 to reduce the temperature of rotor 102 and permanent magnets 88.

Thermal management system 134 also includes an exhaust duct 140 in airflow communication with rotor shaft 104. The exhaust duct 140 extends to the core air flow path 37 to exhaust the hot air to the core air flow path 37. For the depicted embodiment, the inlet duct 136 is in airflow communication with the opening 138 through the rotor shaft 104 at a location forward of the rotor 102 of the rotor assembly 82, and the exhaust conduit 140 is in airflow communication with the opening 138 of the rotor shaft 104 at a location downstream of the rotor 102 of the rotor assembly 82. However, in other embodiments, other configurations are contemplated.

Notably, for example, referring briefly to the labeled circle a in fig. 3, the rotor 102 is formed of a plurality of laminations 142 that fit closely to the rotor shaft 104. The torque of permanent magnet motor 80 is transmitted through this connection between rotor shaft 104 and laminations 142 of rotor 102. Additionally, given this relatively tight fit, heat may be transferred by conduction between the laminations 142 of the rotor 102 and the rotor shaft 104, and thus to the cooling fluid flowing through the openings 138 in the rotor shaft 104.

To increase the temperature of the permanent magnets 88 of the rotor assembly 82 of the exemplary embodiment of fig. 3 (i.e., in response to a determination of a fault condition of the permanent magnet motor 80), the system may use the thermal management system 134 (i.e., reduce the operability of the thermal management system 134) to reduce cooling of the permanent magnet motor 80. For example, the system may shut off or reduce the flow of cooling air through the inlet duct 136 to the opening 138 of the rotor shaft 104, allowing for increased temperature and loss of magnetization of the permanent magnets 88 of the rotor assembly 82. Additionally or alternatively, the system may bypass a heat exchanger that cools air provided through the inlet duct 136.

More specifically, for the depicted embodiment, the valve 142 is provided within the inlet conduit 136 of the thermal management system 134 or is otherwise operable with the inlet conduit 136 of the thermal management system 134. The valve 142 may also be operatively connected to the controller 124 through a wireless communication network. The valve may close or reduce the flow of cooling air through the inlet duct 136 to provide such an increase in the temperature of the permanent magnet 88.

Additionally or alternatively, thermal management system 134 may be configured to provide a heated fluid to permanent magnet motor 80 to increase the temperature of permanent magnet 88. More specifically, for the depicted embodiment, the thermal management system 134 is selectively in airflow communication with a source of high temperature fluid via a high temperature fluid conduit 144, and more specifically, with a source of high temperature bleed air stream via the high temperature fluid conduit 144. For the illustrated embodiment, the source of the high temperature bleed air stream is the turbine section of the turbofan engine 10. With such a configuration, valve 142 of thermal management system 134 may switch the airflow source from a relatively cool airflow source (providing the cooling airflow discussed above) to the high temperature bleed air airflow source such that thermal management system 134 provides a heating fluid/heating airflow/high temperature bleed air flow to permanent magnet motor 80, and more specifically to opening 138 through rotor shaft 104 of rotor assembly 82. This may further and more quickly increase the temperature of the permanent magnet 88 to demagnetize such permanent magnet 88. It is noted that in other embodiments, the high temperature fluid source may be any other suitable high temperature fluid source (e.g., exhaust, compressor, etc.).

Referring now specifically to FIG. 4, exemplary turbofan engine 10 also includes a thermal management system 134 for permanent magnet motor 80. Thermal management system 134 is configured to provide a cooling fluid to an opening 138 through rotor shaft 104 of rotor assembly 82 of permanent magnet motor 80. The depicted thermal management system 134 is configured as a closed loop system, circulating and reusing cooling fluid through a thermal bus 146. For example, the cooling fluid may be a lubricating oil such that thermal management system 134 shares functionality with, for example, a lubricating oil system for one or more sections of turbofan engine 10.

The thermal management system 134 additionally includes a heat sink heat exchanger 148 in thermal communication with the cooling fluid flowing through the thermal bus 146. The radiator heat exchanger 148 is additionally in thermal communication with a radiator system 150. The radiator system 150 may include any suitable source of relatively cold fluid, such as bypass airflow, compressor bleed airflow, fuel, and the like. Accordingly, the radiator heat exchanger 148 is configured to transfer heat from the cooling fluid in the thermal bus 146 of the thermal management system 134 to the relatively cool fluid of the radiator system 150. In this manner, thermal management system 134 may maintain the temperature of permanent magnet motor 80 within a desired operating temperature range.

As shown, the radiator system 150 includes a main line 152, a bypass line 154, and a bypass valve 156 (or more precisely a pair of bypass valves 156). To increase the temperature of the permanent magnets 88 of the rotor assembly 82 of the exemplary embodiment of fig. 4 (i.e., in response to a determination of a fault condition of the permanent magnet motor 80), the system may again reduce the cooling of the permanent magnets 88 of the permanent magnet motor 80 using the thermal management system 134 (i.e., reducing the operability of the thermal management system 134). More specifically, the system may actuate a bypass valve 156 of the radiator system 150 such that relatively cool fluid passing through the main line 152 of the radiator system 150 flows through a bypass line 154 bypassing the radiator heat exchanger 148 of the thermal management system 134. In this manner, the cooling fluid flowing through thermal bus 146 of thermal management system 134 may not be able to reject heat from permanent magnet motor 80. Thus, the cooling fluid, and hence the permanent magnet motor 80, may continue to increase in temperature and the magnetism of the permanent magnets 88 may be reduced or eliminated.

It is noted that although the bypass function is provided by the heat sink system 150 for the illustrated embodiment, in other embodiments the bypass function may instead be built into the thermal bus 146 of the thermal management system 134. Additionally, in certain example embodiments, instead of bypassing the radiator heat exchanger, the system may reduce the flow of cooling fluid through the radiator system 150, reduce the flow of cooling fluid through the thermal bus 146, or both.

Referring now specifically to fig. 5, an exemplary permanent magnet electric machine 80 as described includes a stator assembly 84 having a stator 106 and a rotor assembly 82 having a rotor 102. Moreover, as will be appreciated from, for example, fig. 5, stator 106 of stator assembly 84 and rotor 102 of rotor assembly 82 together generally define an air gap 158 therebetween along radial direction R of exemplary turbofan engine 10. During operation of the permanent magnet motor 80, the rotor assembly 82 will rotate relatively quickly relative to the stator assembly 84. Additionally, the air gap 158 defined between the stator 106 and the rotor 102 may be relatively small. Further, the system generally includes a fluid conduit 160 in fluid communication with the air gap 158.

To increase the temperature of the permanent magnets 88 of the rotor assembly 82 of the exemplary embodiment of fig. 5 (i.e., in response to a determination of a fault condition of the permanent magnet motor 80), the system may inject fluid into the air gap 158 of the permanent magnet motor 80 using fluid conduits 160. The fluid injected into air gap 158 may create an increased amount of friction, thus increasing the temperature of permanent magnets 88 of rotor assembly 82 of permanent magnet motor 80 and reducing or eliminating the magnetism of such permanent magnets 88.

Notably, in certain exemplary embodiments, the injected fluid may be air. However, in other embodiments, any other suitable fluid may be used. For example, in certain embodiments, the fluid may define a viscosity greater than that of air (e.g., at least 10% greater, 20% greater, 50% greater, or 100% greater, and up to, for example, 5,000% greater), further increasing the amount of friction generated and the amount of heat added to permanent magnet motor 80.

It should be appreciated that in at least some exemplary embodiments, features from the configurations depicted in fig. 2-5 can be combined to produce yet further embodiments. Additionally, in other embodiments, the system for heating the permanent magnet 88 discussed with reference to one figure may be combined with the manner for heating the permanent magnet 88 discussed with reference to a different figure. For example, the induction system described above with reference to fig. 2 may be used in conjunction with thermal management system 134 described above with reference to fig. 4.

Further, it should be understood that the illustrated permanent magnet motor 80 is provided by way of example only. In other embodiments, permanent magnet motor 80 may be configured as an "external" motor (wherein the rotor assembly is disposed outside of the stator assembly), permanent magnet motor 80 may be configured as an axial flow motor (wherein the rotor and stator are disposed in an axial direction and have an air gap therebetween having a generally circular shape), and so forth.

Referring now to fig. 6, a flowchart of a method 200 for operating a permanent magnet machine of an engine according to an exemplary aspect of the present disclosure is provided. In at least certain exemplary aspects, the permanent magnet motor and motor operated using method 200 may be constructed in accordance with one or more of the exemplary permanent magnet motors and motors described above with reference to fig. 1-5. Accordingly, it should be appreciated that, in at least certain exemplary aspects, the engine may be a gas turbine engine, such as one of a turboshaft engine, a turboprop engine, a turbojet engine, or a turbofan engine.

For the exemplary aspect depicted in fig. 6, method 200 generally includes determining a fault condition of the permanent magnet motor at (202). More specifically, for the exemplary aspect shown, determining a fault condition of the permanent magnet motor at (202) includes determining an internal coil fault of the permanent magnet motor at (204). An internal coil fault may designate a sub-winding short circuit fault, as described in more detail above. However, in other exemplary aspects, the fault condition may be any other suitable fault condition.

In at least certain example aspects, determining a fault condition of the permanent magnet electric machine at (202) may include receiving data indicative of the fault condition by one or more sensors of a stator assembly operatively coupled to the permanent magnet electric machine, electrical wires of an electrical transmission bus (electrically coupled to the electrical wires of the permanent magnet electric machine), various power electronics of the electrical transmission bus, or the like. For example, in at least certain exemplary aspects, this data may be used in conjunction with various operating conditions of the engine, such as a rotational speed of the engine (e.g., a rotational speed of one or more shafts of the engine), a temperature within the engine (e.g., a compressor inlet temperature, a compressor discharge temperature, a turbine inlet temperature, a turbine discharge temperature, etc.), a pressure within the engine, etc., to determine a fault condition. For example, if the engine is operating in a manner consistent with a large resistance on the engine, and the amount of power drawn by the permanent magnet machine is less than an expected amount, a fault condition may be determined.

Still referring to fig. 6, method 200 further includes, at (206), in response to determining the fault condition of the permanent magnet motor at (202), reducing the magnetic properties of the one or more permanent magnets of the permanent magnet motor by increasing the temperature of the one or more permanent magnets. More specifically, for the exemplary aspect shown, reducing the magnetic properties of the one or more permanent magnets at (206) by increasing the temperature of the one or more permanent magnets includes increasing the temperature of a rotor assembly of the permanent magnet machine, which includes the one or more permanent magnets, at (208). For example, the rotor assembly may include a rotor formed from a plurality of axially arranged laminations configured to mount a plurality of circumferentially arranged permanent magnets therein. A plurality of axially arranged laminations may be fitted to the rotor shaft as discussed in more detail above with reference to fig. 1-5.

It should be appreciated that, for the exemplary aspect shown, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets at (206) includes adding between about 5 kilowatts and about 500 kilowatts of heat at (210). The heat added to increase the temperature of the one or more permanent magnets and decrease the magnetic properties of the one or more permanent magnets may be sufficient to raise the temperature of the one or more permanent magnets to a temperature that approaches or exceeds the curie temperature for such permanent magnets. In this way, the permanent magnet may irreversibly demagnetize or reduce the magnetic properties.

Further, for the exemplary aspect of the method 200 depicted in fig. 6, a number of different ways are contemplated for reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets at (206). For example, in the exemplary aspect of the depicted method 200, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets at (206) may include driving current through a stator assembly of the permanent magnet motor to induce eddy current losses at (212). More specifically, it is to be appreciated that the permanent magnet motor defining a designed current frequency operating range and driving current through a stator assembly of the permanent magnet motor to cause eddy current losses at (212) can include driving current through the stator assembly of the permanent magnet motor at a frequency different from the designed current frequency operating range, and more specifically driving current through the stator assembly of the permanent magnet motor at (214) at a frequency greater than the designed current frequency operating range. As described above, the relatively high frequency current provided to the stator assembly will cause eddy current losses within the permanent magnet machine, thereby increasing the temperature of the permanent magnet machine.

Additionally or alternatively, reducing the magnetism of the one or more permanent magnets at (206) by increasing the temperature of the one or more permanent magnets may include providing a heated fluid to the permanent magnet motor at (216). For example, in at least some example aspects, providing heating fluid to the permanent magnet motor at (216) may include providing a bleed air flow to the permanent magnet motor at (218). The bleed air stream may be a relatively high temperature air stream discharged from, for example, a compressor in a compressor section of the engine, a turbine in a turbine section of the engine, or an exhaust of the engine. The heated fluid provided to the permanent magnet machine at (216) may be provided using a thermal management system, and may be provided to an area surrounding a rotor assembly of the permanent magnet machine, to an opening through a rotor shaft of the rotor assembly of the permanent magnet machine, or to any other suitable location capable of increasing the temperature of the one or more permanent magnets.

Additionally or alternatively, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets at (206) may include reducing cooling of the permanent magnet machine using (i.e., reducing operability of) a thermal management system of the permanent magnet machine at (220). For example, in certain exemplary aspects, reducing cooling of the permanent magnet motor at (220) may include bypassing a heat sink heat exchanger of a thermal management system of the permanent magnet motor at (222). Additionally or alternatively, however, reducing cooling of the permanent magnet electric machine using the thermal management system at (220) may include, for example, slowing or stopping cooling flow through the thermal management system (e.g., for an open-loop or closed-loop thermal management system), slowing or stopping cooling flow from the thermal management system to the permanent magnet electric machine (e.g., for an open-loop thermal management system), and/or the like.

By reducing cooling of the permanent magnet machine using the thermal management system at (220), heat generated by operation of the permanent magnet machine may be kept with the permanent magnet machine, thereby increasing the temperature of the one or more permanent magnets and reducing the magnetic properties of such one or more permanent magnets.

Additionally or alternatively, reducing the magnetism of the one or more permanent magnets at (206) by increasing the temperature of the one or more permanent magnets may include injecting a fluid into an air gap of the permanent magnet machine at (224). In certain exemplary aspects, the fluid may be air. However, in other exemplary aspects, the fluid may define a viscosity greater than that of air. Regardless, it should be appreciated that the air gap of the permanent magnet machine defined between the rotor of the rotor assembly and the stator of the stator assembly may be relatively small such that introducing the fluid therein at (224) may increase the amount of friction generated during operation of the permanent magnet machine, thereby increasing the heat generated and the temperature of the one or more permanent magnets, and thereby reducing the magnetic properties of the one or more permanent magnets. It is noted that although not shown, the method 200 may further include withdrawing all, substantially all, or at least a portion of the fluid from the air gap once the permanent magnet has been demagnetized to a desired degree (which may be determined in any suitable manner, such as by sensing a resistance on the engine, a temperature of the permanent magnet, and/or a duration of temperature rise of the permanent magnet, etc.). This may reduce the amount of viscous drag produced by the electric machine on the engine.

As discussed above with reference to certain of the above embodiments, the rotor assembly of the permanent magnet electric machine may include a rotor and a shaft formed from a plurality of laminations. The plurality of laminations may be fitted to the shaft such that heat may be exchanged between the plurality of laminations and the shaft by conduction. Thus, cooling flow (e.g., air flow, coolant flow, etc.) through the openings of the shaft of the rotor assembly may receive heat transferred from the laminations to the shaft. For the exemplary aspect of the method 200 depicted in fig. 6, reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets at (206) may include reducing the contact pressure between the plurality of laminations and the shaft at (226). By reducing the contact pressure between the plurality of laminations and the shaft at (226), the heat rejection path from the permanent magnet/rotor assembly to the coolant flow may be broken. More specifically, by reducing the contact pressure between the plurality of laminations and the shaft at (226), conductive heat transfer between the laminations and the shaft can be inhibited such that the temperature of the laminations and the one or more permanent magnets mounted thereto are increased as needed. In at least certain exemplary aspects, reducing the contact pressure between the plurality of laminations and the shaft at (226) can be achieved by forming the laminations and shaft of a particular material having a desired coefficient of thermal expansion. For example, the laminations may be designed to expand more than the shaft at certain temperatures, such that once the shaft and laminations reach such temperatures (which may indicate a fault condition of the permanent magnet machine), the contact pressure between the plurality of laminations and the shaft is reduced (and possibly even gaps are formed between them), thereby further increasing the temperature of the laminations and the plurality of permanent magnets as needed.

However, it should be understood that in other exemplary aspects any other suitable method may be used. For example, in other exemplary aspects, any other suitable method for increasing the temperature of one or more permanent magnets of a permanent magnet motor in response to a determination of a fault condition of the permanent magnet motor may be provided, and/or combinations of the above methods may be used.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Further aspects of the invention are provided by the subject matter of the following clauses:

1. a method for operating a permanent magnet motor of an engine, the method comprising: determining a fault condition of the permanent magnet motor; and in response to determining the fault condition of the permanent magnet motor, reducing the magnetism of one or more permanent magnets of the permanent magnet motor by increasing the temperature of the one or more permanent magnets.

2. The method according to any preceding item, wherein the engine is an internal combustion engine.

3. The method according to any preceding item, wherein the engine is at least one of a turboshaft engine, a turboprop engine, or a turbofan engine.

4. The method according to any of the preceding claims, wherein the engine is configured to produce a maximum amount of power during operation, wherein the permanent magnet motor is capable of extracting a maximum amount of power from the engine, and wherein the maximum amount of power that the permanent magnet motor is capable of extracting from the engine is between about 2.5% and about 75% of the maximum amount of power that the engine is configured to produce during operation.

5. The method according to any preceding claim, wherein the maximum amount of power that the permanent magnet machine can extract from the engine is greater than about 25% of the maximum amount of power that the engine is configured to produce during operation.

6. The method of any preceding item, wherein determining the fault condition of the permanent magnet motor comprises determining an internal coil fault of the permanent magnet motor.

7. The method of any preceding item, wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises driving a current through a stator assembly of the permanent magnet machine to cause eddy current losses in a rotor assembly of the permanent magnet machine.

8. The method according to any of the preceding claims, wherein the permanent magnet machine defines a designed current frequency operating range, and wherein driving current through the stator assembly of the permanent magnet machine to cause eddy current losses comprises driving current through the stator assembly of the permanent magnet machine at a frequency different than the designed current frequency operating range.

9. The method of any preceding item, wherein reducing the magnetism of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises providing a heated fluid to the permanent magnet motor.

10. The method according to any preceding item, wherein providing the heating fluid to the permanent magnet motor includes providing bleed air to the permanent magnet motor.

11. The method of any preceding item, wherein reducing the magnetism of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises reducing cooling of the permanent magnet machine using a thermal management system.

12. The method of any preceding item, wherein reducing the cooling of the permanent magnet motor using the thermal management system comprises bypassing a heat sink heat exchanger of the thermal management system.

13. The method of any preceding claim, wherein reducing the magnetism of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises injecting a fluid into an air gap of the permanent magnet machine.

14. The method according to any preceding item, wherein the fluid defines a viscosity greater than that of air.

15. The method of any preceding item, wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises adding between about 5 kilowatts and about 500 kilowatts of thermal energy.

16. The method according to any preceding item, wherein the permanent magnet machine comprises a rotor assembly having a plurality of laminations and a shaft, wherein the plurality of laminations fit onto the shaft, and wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises reducing a contact pressure between the plurality of laminations and the shaft.

17. The method of any preceding claim, wherein the engine comprises a thermal management system for providing cooling fluid through one or more openings in the shaft.

18. An engine defining an axis, comprising: a fixing member; a rotating member that is rotatable about the axis of the engine relative to the stationary member; a permanent magnet electric machine comprising a stator assembly coupled to the stationary component and a rotor assembly coupled to the rotating component, the rotor assembly comprising one or more permanent magnets; a controller operable with the permanent magnet motor, the controller configured to determine a fault condition of the permanent magnet motor and increase a temperature of the one or more permanent magnets of the permanent magnet motor in response to determining the fault condition.

19. An engine according to any preceding claim, further comprising: an electrical transmission bus in electrical communication with the permanent magnet motor, wherein the controller is further operatively connected to the electrical transmission bus.

20. The engine of any preceding item, wherein the engine is configured to produce a maximum amount of power during operation, wherein the permanent magnet motor is capable of extracting a maximum amount of power from the engine, and wherein the maximum amount of power that the permanent magnet motor is capable of extracting from the engine is between about 2.5% and about 75% of the maximum amount of power that the engine is configured to produce during operation.

Claims

1. A method for operating a permanent magnet motor of an engine, the method comprising:

determining a fault condition of the permanent magnet motor; and

in response to determining the fault condition of the permanent magnet motor, reducing a magnetism of one or more permanent magnets of the permanent magnet motor by increasing a temperature of the one or more permanent magnets.

2. The method of claim 1, wherein the engine is an internal combustion engine.

3. The method of claim 1, wherein the engine is at least one of a turboshaft engine, a turboprop engine, or a turbofan engine.

4. The method of claim 1, wherein the engine is configured to generate a maximum amount of power during operation, wherein the permanent magnet motor is capable of extracting a maximum amount of power from the engine, and wherein the maximum amount of power that the permanent magnet motor is capable of extracting from the engine is between about 2.5% and about 75% of the maximum amount of power that the engine is configured to generate during operation.

5. The method of claim 4, wherein the maximum amount of power that the permanent magnet motor can extract from the engine is greater than approximately 25% of the maximum amount of power that the engine is configured to produce during operation.

6. The method of claim 1, wherein determining the fault condition of the permanent magnet motor comprises determining an internal coil fault of the permanent magnet motor.

7. The method of claim 1, wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises driving a current through a stator assembly of the permanent magnet machine to induce eddy current losses in a rotor assembly of the permanent magnet machine.

8. The method of claim 7, wherein the permanent magnet motor defines a designed current frequency operating range, and wherein driving current through the stator assembly of the permanent magnet motor to cause eddy current losses comprises driving current through the stator assembly of the permanent magnet motor at a frequency different than the designed current frequency operating range.

9. The method of claim 1, wherein reducing the magnetic properties of the one or more permanent magnets by increasing the temperature of the one or more permanent magnets comprises providing a heated fluid to the permanent magnet motor.

10. The method of claim 8, wherein providing the heating fluid to the permanent magnet motor comprises providing bleed air to the permanent magnet motor.